A multi-layer piezoelectric element including a stacked body in which a plurality of piezoelectric layers are laminated with internal electrode layers interposed therebetween, a pair of external electrodes being formed on side faces of the stacked body, has conventionally been known. This multi-layer piezoelectric element has a structure in which an external electrode with positive polarity and an external electrode with negative polarity are respectively formed on facing side faces of the stacked body, and the internal electrode layers are electrically connected to the external electrodes alternately. By applying a voltage to the piezoelectric layers between the internal electrode layers via the external electrodes, displacement is obtained in a stacked direction thereof. The key factor of this displacement corresponds to movement of a domain wall which is present in crystal particles of the piezoelectric layers which constitute a stacked body. It is known that the movement of this domain wall is constrained by a particle boundary between crystal particles (see Patent Literature 1).